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Major Components of a Map
 Scale bar
 legend
 North Arrow
 Title
 Discription
 Source
 Locator Map
 Border
 Credit

Map Geometry
Symbols occupy more space than they generally take up based on the scale
Linear widths, sometimes rivers are lines on a map other times they are polygons (question of scale and what is the real width of the river)
Same is true for roads

Elementary Geometric Operations (Linear Features)

Elementary Geometric Operations
(Point Features)

Elementary Geometrick Operations
(Area Features)



Meridian
A plane that passes through the center of the Earth
For reference in projection terms a meridian passes through the poles
Since all are equal a prime meridian had to be selected
Longitude lines of the Earth’s graticule

Parallel
Lines placed at right angles to the meridians
The equator is a parallel and is the main reference point for projections
Latitude lines of the Earth’s graticule

Coordinate System
Global systems
– Most commonly used latitude and longitude
 • Reno, NV
 – Latitude 39° 30’ 30” North
 – Longitude 119° 48’ 30” West
• Degrees, Minutes, Seconds (dms)
 • Decimal Degrees (dd)
 – Latitude 39.508333333
 – Longitude 119.80833333
 • Conversion to decimal degrees
 – decimal deg. = degrees + (minutes / 60) + (seconds / 3600)

Spheroid
A threedimensional shape obtained by rotating an ellipse about its minor axis, with dimensions that either approximate the earth as a whole, or with a part that approximates the corresponding portion of the geoid.
The shape and size of a coordinate system is defined by the spheroid
Smaller scale systems can assume sphere shape for earth (more on that later)
Most created with a specific region in mind

Geoid
Earth not a true ellipse or sphere, but has an irregular shape. This shape is called a geoid.
Think in terms of the highest mountain peak and the lowest ocean valley

Conical Map Projections
 Albers equalarea
 Conical can also be good for distances
 Scale and shape distorted

Cylindrical
 Distortion different close to poles
 Meridians are now the important points
 UTM zones run northsouth with a central meridian

Azimuthal
 Projections onto a plane
 Good for direction
 Map distances can be computed by a function

